1. Field of the Invention
The present invention relates to a driving mechanism that drives a driven member by using piezoelectric elements.
2. Description of the Related Art
In the field of multi-degree-of-freedom control systems represented by six-degree-of-freedom positioning mechanisms used for visual line change control on surveillance cameras and the like and for semiconductor manufacturing apparatuses, a driving mechanism or motor system having an arrangement in which single-axis driving motors are connected in series and stacked on each other has been widely used. Recently, in particular, attention has been paid to research and development of a mechanism that can perform multi-degree-of-freedom driving at high speed with high accuracy by using piezoelectric elements for a driving source in consideration of reductions in size and weight and an increase in accuracy. As support structures for conventional typical mechanisms of this type, there have been proposed a structure using a parallel plate and a radiation plate (JP-A 63-137306 (KOKAI)), a structure using an elastic hinge (the Proceedings of the Japan Society for Precision Engineering Spring Conference (1987)), pp. 499-500), and a structure using a parallel mechanism (Journal of the Japan Society for Precision Engineering Vol. 65 No. 10 (1999), pp. 1445-1449).
However, each of these conventional structures has the following problems and is not necessarily satisfactory. (A) The arrangement in which single-axis actuators are connected in series and stacked on each other makes it difficult to achieve a further increase in speed (a decrease in rigidity) and a further decrease in size. (B) Because of large axis interference, it is difficult to simplify a controller and increase its speed and accuracy. (C) The range of movement is narrow, and hence versatility is low. The conventional structure using the parallel plate and the radiation plate has a limited range of application because of problems (A) and (C) described above in particular. The structure using the elastic hinge and the structure using the parallel mechanism have limited ranges of application mainly because of problems (B) and (C) described above.